Variable displacement compressor having refrigerant flowing function in driving shaft

ABSTRACT

Provided is a variable displacement compressor comprising a cylinder block having a plurality of cylinder bores, housing, a drive shaft rotatably supported by the cylinder block, a lug plate, a swash plate being rotated by the lug plate to vary a tilt angle thereof, a sleeve reciprocally moving along the drive shaft, an addition discharge passage for fluid communication between the swash plate chamber and the suction chamber, characterized in that the variable displacement compressor comprises: a communication hole being a part of the addition discharge passage and formed in the drive shaft in its longitudinal direction; and a lateral communication passage formed at the lateral side of the drive shaft to be connected to the communication hole such that the lateral communication passage is opened and closed by reciprocal movement of the sleeve. Therefore, even though the swash plate is at position of the maximum tilt angle, the temperature of the swash plate chamber is prevented from rising by making a smooth refrigerant flow from the swash plate chamber to the suction chamber, thereby maintaining higher lubrication ability.

TECHNICAL FIELD

This present invention relates to a variable displacement compressorhaving a refrigerant flow function in a drive shaft, more particularlyto a variable displacement compressor capable of maintaining higherlubrication ability by making the smooth flow of refrigerant from aswash plate chamber to a suction chamber, at about maximum tilt angle ofa swash plate, to prevent a temperature of the swash plate chamber fromrising excessively.

BACKGROUND ART

Recently, a lot of research with respect to a swash plate type variabledisplacement compressor that is used to air conditioning systems forvehicles has been developed. It changes the tilt angle of the swashplate by a control valve depending on a change of thermal load, andcontrols strokes of pistons to accomplish precise temperature control.At the same time, the tilt angle is continuously varied to reduce abrupttorque fluctuation of an engine caused by the compressor, therebyimproving ride comfort of a vehicle.

A swash plate type variable compressor of the prior art includes aspecial oil separator for separating gas refrigerant and oil fromremaining refrigerant in a swash plate chamber such that the separatedgas refrigerant is moved to a suction chamber and the separated oil isreturned to the swash plate chamber for lubrication.

However, in Korean Registration Patent No. 606641 (hereinafter, referredto as prior art), a structure that can function as separating the oilwithout the oil separator is disclosed. Hereinafter, constitution of thestructure will be described roughly according to FIGS. 1 and 2.

As shown in FIGS. 1 and 2, when a partial high-pressure refrigerant of adischarge chamber 133 is supplied to a swash plate chamber 120 a by theoperation of control valve 138, the pressure inside the swash platechamber 120 a is changed and oil is separated while mist typerefrigerant of the inside of the swash plate chamber 120 a passesthrough an addition discharge passage 145, and then refrigerant gas isreturned to the suction chamber 132.

In the concrete, the refrigerant of the inside of the swash platechamber 120 a passes through a first separation hole 185 a and a secondseparation hole 185 b formed in a lug plate 180, which are parts of theaddition discharge passage 145. In this case, the oil and therefrigerant are separated by an action of centrifugal force due torotation of the lug plate 180, the separated oil is slidably contactedwith an inner periphery of the first separation hole 185 a to besupplied to the swash plate chamber 120 a, and the separated gasrefrigerant is discharged to the suction chamber 132 of lower pressurethrough the second separation hole 185 b. As a result; oil amount of theinside of the swash plate chamber 120 a becomes more plentiful, andthereby it is possible to smoothly lubricate. As this, oil separationcan be accomplished by the separation holes formed in the lug plate,without using oil separator.

DISCLOSURE Technical Problem

However, according to the above prior art, when the swash plate reachesat the maximum tilt angle, since the pressure of the inside of the swashplate chamber is lowered, the refrigerant can t smoothly flow in thesuction chamber through a communication hole 142 formed in the drivingshaft. Thus, according to the prior art, when the swash plate is at themaximum tilt angle, the lubrication ability is lowered due to excessiverise of temperature of the inside of the swash plate chamber, so thatdurability of the compressor is significantly decreased.

An object of the present invention is to provide a variable compressorcapable of maintaining higher lubrication ability by preventingtemperature of the swash plate chamber from rising while making a smoothrefrigerant flow from a swash plate chamber to a suction chamber, eventhough the swash plate is at the maximum tilt angle.

Technical Solution

An aspect of the present invention provides a variable displacementcompressor comprising a cylinder block having a plurality of cylinderbores, a front housing disposed at a front end of the cylinder block toform a swash plate chamber, a drive shaft rotatably supported by thecylinder block, a lug plate fixedly installed at the drive shaft in theswash plate chamber of the front housing, a rear housing having asuction chamber and discharge chamber and being disposed at a rear endof the cylinder block, a swash plate being rotated by the lug plate tovary a tilt angle thereof, pistons coupled to the swash plate to bereciprocally accommodated in the cylinder bores, a sleeve reciprocallymoving along the drive shaft, a spring elastically supporting the sleevearound the drive shaft, an addition discharge passage connect the swashplate chamber and the suction chamber, characterized in that thevariable displacement compressor comprises: a communication hole 142being a part of the addition discharge passage and formed in the driveshaft in its longitudinal direction; and a lateral communication passageformed at the lateral side of the drive shaft to be connected to thecommunication hole such that the lateral communication passage is openedand closed by reciprocal movement of the sleeve.

Here, the sleeve may be moved at more than a predetermined angle of theswash plate to open the communication passage.

In addition, the addition discharge passage may includes a firstseparation hole formed through the lug plate, a second separation holeformed in the lug plate to connect the first separation hole and thecommunication hole, and a connection hole formed in the drive shaft tobe connected to the separation hole.

DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-sectional view of a variable displacementcompressor according to a prior art;

FIG. 2 is a cross-sectional view of refrigerant flow structure of FIG.1;

FIG. 3A is a detailed sectional view of swash plate of a minimum tiltangle and its peripheral components in a variable displacementcompressor according to an exemplary embodiment of the presentinvention; and

FIG. 3B is a detailed sectional view of swash plate of a maximum tiltangle and its peripheral components in a variable displacementcompressor according to an exemplary embodiment of the presentinvention.

BEST MODE

Hereinafter, exemplary embodiments of the present invention will bedescribed according to the accompanying drawings. The components thatmay be embodied in the above prior art are denoted by the same referencenumerals as the prior art.

As shown in FIGS. 1, 3A and 3B, a swash plate type variable displacementcompressor 1000 includes a cylinder block 110 having a plurality ofcylinder bores 110 a extended along a longitudinal direction of thecompressor, a front housing 120 disposed at a front end of the cylinderblock 110, a drive shaft 140 rotatably supported by the cylinder block110 and the front housing 120, a lug plate 180 fixedly installed at thedrive shaft 140 in a swash plate chamber 120 a of the front housing 120,a rear housing 130 having a suction chamber 132 and discharge chamber133 and being disposed at a rear end of the cylinder block 110, a swashplate 150 having a disc shape and being rotated by the lug plate 180 tovary a tilt angle thereof, a spring 170 supported between the lug plate180 and the swash plate 150, and pistons 200 coupled to the swash plate150 to be reciprocally accommodated in the cylinder bores 110 a.

Although the pistons 200 are slidably coupled to the swash plate 150 viashoes 201, a connection constitution including a long connection rod anda guiding groove formed at an end thereof may be allowed in stead of theshoes 201.

The suction chamber 132 and the discharge chamber 133 are respectivelyformed in the rear housing 130, and a suction port 131 a and a dischargeport (not shown) are respectively formed in the valve plate 131 toconnect the cylinder bore 110 a and the suction chamber 132, and betweenthe cylinder bore 110 a and the discharge chamber 133 respectively.Further, a suction valve and a discharge valve are respectively providedin the suction port 131 a and the discharge port formed in the valveplate 131 to open and close the suction port 131 a and the dischargeport by a pressure change due to reciprocal movement of the pistons 200.

In addition, an addition discharge passage 145 is provided to connectthe swash plate chamber 120 a and the suction chamber 132, and a controlvalve 138 is installed on the way of a suction passage 137.

The addition discharge passage 145 comprises a first separation hole 185a and a second separation hole 185 b formed in the lug plate 180, and aconnection hole 147 and a communication hole 142 formed in drive shaft140.

The communication hole 142 as a part of the addition discharge passage145 is formed in the drive shaft 140 in a longitudinal direction toconnect the swash plate chamber 120 a and the suction chamber 132.

The first separation hole 185 a penetrates the lug plate 180 d from thefront side to the rear side to be in communication with the swash platechamber 120 a. The second separation hole 185 b is formed in the Jugplate 180 to connect the first separation hole 185 a and thecommunication hole 142.

The connection hole 147 is formed in the drive shaft 140 to connect thesecond separation hole 185 b and the communication hole 142.

The first separation hole 185 a and the second separation hole 185 bseparate an oil from mist phase refrigerant including the oil, and theseparated gas refrigerant flows toward the suction chamber 132 via theconnection hole 147 and the communication hole 142 of the drive shaft140.

A lateral communication passage 143 which is connected to thecommunication hole 142 is formed at lateral side of the drive shaft 140such that the lateral communication passage 143 is opened and closed byreciprocal movement of the sleeve 148 due to tilt movement of the swashplate 150.

In particular, it is preferable that the sleeve 148 closes the lateralcommunication passage 143 at a minimum tilt angle of the swash plate150, and opens the lateral communication passage 143 at a maximum tiltangle of the swash plate 150 while moving along the drive shaft 140.

That is, when the swash plate 150 reaches at the maximum tilt angle,since the communication passage 143 is opened, the refrigerant in theswash plate chamber 120 a enters the suction chamber 132 through thelateral communication passage 143 and the communication hole 142,thereby, it is possible that the refrigerant flows more smoothly.

The lateral communication passage 143 may be opened prior to the maximumtilt angle of the swash plate 150.

Hereinafter, operation of the variable displacement compressor having arefrigerant flow function in a drive shaft according to an exemplaryembodiment of the present invention will be described.

As shown in FIG. 3B, when the high pressure refrigerant of the dischargechamber 133 is supplied to the inside of the swash plate chamber 120 ain accordance with the operation of the control valve 138, therefrigerant in the swash plate chamber 120 a enters the suction chamber132 via the addition discharge passage 145 while the pressure of theinside of the swash plate chamber 120 a is changed.

In the concrete, first, the refrigerant passes through the firstseparation hole 185 a and the second separation hole 185 b, which areparts of the addition discharge passage 145 and formed in the lug plate180. In this case, the oil and the refrigerant are separated from eachother by an action of centrifugal force due to rotation of the lug plate180. The separated oil is supplied to the swash plate chamber 120 awhile sliding in contact with a inner periphery of the first separationhole 185 a, and the separated gas refrigerant is discharged to thesuction chamber 132 of lower pressure through the second separation hole185 b. As a result, oil amount of the inside of the swash plate chamber120 a becomes more plentiful, and thereby, smooth lubrication ispossible.

As shown in FIG. 3B, when the swash plate 150 is reached at the maximumtilt angle, the sleeve 148 is moved forward to open the lateralcommunication passage 143 covered with the sleeve 148 such that therefrigerant of the inside of the swash plate chamber 120 a is dischargedto the suction chamber 132 through the lateral communication passage 143and the communication hole 142.

As this, when the swash plate 150 is at the maximum tilt angle, therefrigerant is discharged through the lateral passage 143 and thecommunication hole 142 of the drive shaft 149, as well as the firstseparate hole 185 a, the second separate hole 185 b, and thecommunication hole 142, and thereby the refrigerant is further smoothlydischarged.

According to the exemplary embodiment of the present invention, when theswash plate 150 is at the maximum tilt angle, the refrigerant flowssmoothly from the swash plate chamber 120 a to the suction chamber 132,thereby preventing the temperature of the inside of the swash platechamber 120 a from rising and maintaining the higher lubricationability.

A point of time when the lateral communication passage 143 is opened bythe sleeve 148 is not necessarily limited to a point of time when theswash plate 150 reaches to about the maximum tilt angle, and apredetermined point of time just prior to the maximum tilt angle of theswash plate 150 can be allowed.

INDUSTRIAL APPLICABILITY

According to the exemplary embodiment of the present invention, eventhough the swash plate is at the position of the maximum tilt angle, thetemperature of the swash plate chamber is prevented from rising bymaking the smooth refrigerant flow from the swash plate chamber to thesuction chamber, thereby maintaining higher lubrication ability.

While this invention has been described with reference to exemplaryembodiment thereof, it will be clear to those of ordinary skill in theart to which the invention pertains that various modification may bemade to the described embodiments without departing from the spirit andscope of the invention as defined in the appended claims and theirequivalents.

1. A variable displacement compressor comprising a cylinder block havinga plurality of cylinder bores, a front housing disposed at a front endof the cylinder block to form a swash plate chamber, a drive shaftrotatably supported by the cylinder block, a lug plate fixedly installedat the drive shaft in the swash plate chamber of the front housing, arear housing having a suction chamber and discharge chamber and beingdisposed at a rear end of the cylinder block, a swash plate beingrotated by the lug plate to vary a tilt angle thereof, pistons coupledto the swash plate to be reciprocally accommodated in the cylinderbores, a sleeve reciprocally moving along the drive shaft, a springelastically supporting the sleeve around the drive shaft, an additiondischarge passage for fluid communication between the swash platechamber and the suction chamber, characterized in that the variabledisplacement compressor comprises: a communication hole being a part ofthe addition discharge passage and formed in the drive shaft in itslongitudinal direction; and a lateral communication passage formed atthe lateral side of the drive shaft to be connected to the communicationhole such that the lateral communication passage is opened and closed byreciprocal movement of the sleeve.
 2. The variable displacementcompressor according to claim 1, wherein the sleeve is moved at morethan a predetermined angle of the swash plate to open the communicationpassage.
 3. The variable displacement compressor according to claim 1,wherein the addition discharge passage includes a first separation holeformed through the lug plate, a second separation hole formed in the lugplate to connect the first separation hole and the communication holeand a connection hole formed in the drive shaft to be connected to theseparation hole.
 4. The variable displacement compressor according toclaim 2, wherein the addition discharge passage includes a firstseparation hole formed through the lug plate, a second separation holeformed in the lug plate to connect the first separation hole and thecommunication hole, and a connection hole formed in the drive shaft tobe connected to the separation hole.